Human microvascular endothelial cells (MvEC) remain largely unstudied due to difficulties in establishing and maintaining cell cultures. The work proposed in this Phase I application is to develop a product consisting of human adipose tissue-derived MvEC and an optimized defined, serum-free culture system. A standard in vitro system will advance research into process and interactions involved in human disease. Cell Systems Corporation has developed and markets on a large scale Human Umbilical Vein Endothelial (HUVE) cells and a defined serum-free HUVE culture system. This medium inhibits non-endothelial cells. Studies on Cell Systems HUVE, including cytokine activation and retroviral transfection, validate the system. The purpose of this Phase I application is to develop a marketable defined system for human MvEC and cell cultures originated and growing in this system. The existence of a standardized system for human HvEC will support research, and will allow results from various laboratories to be more easily compared. Researchers will be able to work MvEC without inventing a culture system of becoming experts in EC biology. Cell culture is a tool, not an end in itself, and we propose to provide a finished, useful tool: researchers can concentrate on experiments, and can spend less time (and money) on cell cultures they need. Cell Systems personnel have extensive experience in culturing and optimizing defined serum-free systems for EC from different species and different vascular beds (current products include Porcine omental and adipose tissue-derived MvEC; and human, bovine, porcine, and canine large-vessel EC). Cell Systems has the infrastructure and background to manufacture and market human EC and its defined culture system.